﻿/*
 * Copyright (c) 1982, 1986, 1993
 *	The Regents of the University of California.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *	This product includes software developed by the University of
 *	California, Berkeley and its contributors.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 *	@(#)tcp_fsm.h	8.1 (Berkeley) 6/10/93
 */

/*
 * TCP FSM state definitions.
 * Per RFC793, September, 1981.
 */

/* 服务端被动建立连接的状态变迁图:
   收到SYN包:CLOSED -> LISTEN -> SYN_RECEIVED
   收到ACK包:SYN_RECEIVED -> ESTABLISHED
*/

#define	TCP_NSTATES	11

#define	TCPS_CLOSED			0	/* closed */
#define	TCPS_LISTEN			1	/* 被动的一方，等待连接  */
#define	TCPS_SYN_SENT		2	/* 主动的一方，发出SYN后进入  */
#define	TCPS_SYN_RECEIVED	3	/* 被动的一方，接收到SYN后进入，发出SYN + ACK  */
/* states < TCPS_ESTABLISHED are those where connections not established */
#define	TCPS_ESTABLISHED	4	/* 连接建立，对于主动的一方发出ACK后进入；对于被动的一方接收到ACK后进入  */
#define	TCPS_CLOSE_WAIT		5	/* 首先接收到FIN的一方，接收到FIN后进入 */
/* states > TCPS_CLOSE_WAIT are those where user has closed */
#define	TCPS_FIN_WAIT_1		6	/* 首先发起FIN的一方，发出FIN后进入 */
#define	TCPS_CLOSING		7	/* 两端同时发起FIN，等待FIN + ACK时，进入 */
#define	TCPS_LAST_ACK		8	/* 其次，发起FIN的一方，发出FIN后进入 */
/* states > TCPS_CLOSE_WAIT && < TCPS_FIN_WAIT_2 await ACK of FIN */
#define	TCPS_FIN_WAIT_2		9	/* 首先发起FIN的一方，接收到FIN + ACK后进入 */
#define	TCPS_TIME_WAIT		10	/* 首先发起FIN的一方，接收到FIN后进入，等待2*msl 后进入CLOSED状态 */

#define	TCPS_HAVERCVDSYN(s)	((s) >= TCPS_SYN_RECEIVED)
#define	TCPS_HAVERCVDFIN(s)	((s) >= TCPS_TIME_WAIT)

#ifdef	TCPOUTFLAGS
/*
 * Flags used when sending segments in tcp_output.
 * Basic flags (TH_RST,TH_ACK,TH_SYN,TH_FIN) are totally
 * determined by state, with the proviso that TH_FIN is sent only
 * if all data queued for output is included in the segment.
 */
u_char	tcp_outflags[TCP_NSTATES] = {
    TH_RST|TH_ACK, 0, TH_SYN, TH_SYN|TH_ACK,
    TH_ACK, TH_ACK,
    TH_FIN|TH_ACK, TH_FIN|TH_ACK, TH_FIN|TH_ACK, TH_ACK, TH_ACK,
};
#endif

#ifdef KPROF
int	tcp_acounts[TCP_NSTATES][PRU_NREQ];
#endif

#ifdef	TCPSTATES
char *tcpstates[] = {
	"CLOSED",	"LISTEN",	"SYN_SENT",	"SYN_RCVD",
	"ESTABLISHED",	"CLOSE_WAIT",	"FIN_WAIT_1",	"CLOSING",
	"LAST_ACK",	"FIN_WAIT_2",	"TIME_WAIT",
};
#endif
